Pilot May Have Failed to Set Flaps : Inadequate Check Prior to Takeoff Indicated in Crash

ROMULUS, Mich. —  Failure by the pilot to deploy the wing flaps of his aircraft may have caused the crash of Northwest Airlines Flight 255 in which at least 154 people died, federal investigators indicated Wednesday night.

John Lauber, head of the National Transportation Safety Board investigating team, said that the “black box” flight data recorder recovered from the aircraft indicated that the flaps and slats were in an “unusual” retracted position when the plane attempted to take off.

He said also that the pilot and first officer may have omitted a mandatory preflight check designed to make certain the flaps and slats were working properly.

Preflight Check

Cockpit conversations taped by the voice recorder recovered from the wreckage indicated that, when the pilot and first officer went through their preflight check, they omitted mention of the flaps and slats, which are included on the checklist, Lauber said.

There was no explanation for those omissions.

Pilots have to rely on instruments to make such checks, because the wings are not visible from the cockpit. Thus, it is not known whether any failure to deploy might have been a deliberate decision on the part of the flight crew, an omission or some mechanical malfunction possibly overlooked during the flight check.

Flaps and slats are large metal surfaces that normally are extended during takeoff to provide a plane with extra lift.

On Wednesday night, Lauber stressed that, although the flight data recorder indicated the flaps and slats were not deployed, further evidence is needed to prove this conclusively.

Unsure of Data

“We can’t even be sure that the data on the flight data recorder accurately reflected the circumstances,” he said.

Lauber said his investigators would have to look at filaments in the cockpit instrument indicator lights, study the wreckage of the control surfaces themselves and compute performance data on the ill-fated flight to see if the black box readings were correct.

The MD-80 jetliner crashed Sunday on takeoff from Detroit’s Metropolitan Airport on a flight to Orange County’s John Wayne Airport.

Wednesday was the third straight night in which investigators offered new evidence as to what may have led to the crash.

On Tuesday night, Lauber had indicated that a weather phenomenon known as wind shear, which can generate powerful down drafts and tail winds, may have contributed. He did not discount wind shear on Wednesday night.

On Monday night, the NTSB member told of evidence that led to early speculation that the jetliner had suffered engine failure. Subsequent investigation seemed to reduce that likelihood, and Lauber said Wednesday night that the data recorder indicated that both engines were producing approximately the same thrust and there was no fire in the engines prior to impact.

In discussing the apparent lack of flap deployment, Lauber called it unusual but noted that “it is a permissible configuration in the aircraft.”

However, aviation sources indicated that a “no-flaps” takeoff would normally be attempted only on extremely long runways with a relatively light load.

Flight 255 took off on a runway of average length--8,500 feet. The plane, while it has an allowable maximum gross weight of 149,500 pounds, weighed only about 5,000 pounds less than that on takeoff, according to records recovered by investigators.

Lauber said evidence was that the plane reached a maximum altitude of 48 feet.

The plane clipped a 41-foot-tall light pole, glanced off a car rental agency building and slammed into an intersection before skidding more than a quarter of a mile down the roadway in a sheet of flame, striking at least three motor vehicles.

Advisories Issued

Lauber said Tuesday night that sensing devices at the airport detected potential wind-shear conditions about a half hour before the crash, and advisories were issued on recorded weather broadcasts usually monitored by pilots before takeoff.

Witness reports of flames surrounding the plane’s left engine on takeoff led to early speculation that the jetliner had suffered engine failure.

But Lauber said preliminary examination found no evidence that either of the plane’s two engines had failed, and aviation experts said the flames may have resulted from an engine backfire.

It’s up to Lauber’s investigators to sort all this out--a job that is expected to take months.

The first step in that process is the collection of evidence, and that’s what the 100 or so investigators are doing right now. That job should be largely completed within about 10 days.

The second step is inspection and interpretation. Some of that takes place at the crash site, some at safety board laboratories in Washington and some at the facilities of the various companies that have manufactured components of the plane.

Voice Recorder Removed

The plane’s cockpit voice recorder was removed from the wreckage and taken to Washington for transcription and analysis. A preliminary transcript disclosed the voice of the plane’s verbal stall alarm before the sound of impact.

The aircraft’s flight data recorder, which contains information on some of Flight 255’s precise headings and control settings in the seconds before the crash, also was sent to Washington.

Lauber said that, although there appeared to be nothing wrong with the flight data recording, “lab difficulties” at the safety board headquarters on Independence Avenue prompted transferal of the “black box” to the manufacturer’s plant for use of the lab facilities there.

The plane’s engines, recovered largely intact, were being transferred to a hangar at Detroit’s Metropolitan Airport on Wednesday. They will receive an overall inspection here, then be hauled to the Pratt & Whitney factory in East Hartford, Conn., where company technicians will join the federal experts in examining every component.

Once all the physical evidence has been examined and interpreted, the safety board will begin its analysis, a third step in the investigative process.

Somewhere along the way, probably in two or three months, public hearings will be scheduled here. Witnesses and other interested parties will be invited to testify.

Several months after that, the safety board will issue a draft report summarizing its findings, listing probable causes for the crash and making recommendations for corrective actions to avoid similar catastrophes.

In the case of the Aeromexico jetliner collision with a light plane over Cerritos, Calif., last Aug. 31 in which 82 died, the draft report was issued in July, about 10 1/2 months after the crash.

Several major areas of confusion remained unresolved Wednesday as the investigators headed back out into the field.

One was the question of exactly how many people had died in the crash. Lauber said this was complicated by at least two factors--the extreme fragmentation of the remains caused by the immense force of the impact and the fact that a number of passengers were believed to be traveling on “frequent flier tickets” provided by others, which made the passenger manifest inaccurate.

Lauber’s latest figures were 153 dead from the plane and one dead on the ground, but others said there may have been more both on the plane and on the ground. Lauber said there may not be an accurate count before the end of the week.

The lone survivor from the plane, Cecilia Cichan, 4, from Tempe, Ariz., remained in serious condition Wednesday at a hospital in nearby Ann Arbor. The severely burned child, who lost both parents and a 6-year-old brother in the crash, was being showered with gifts and cards from well-wishers.

There were several persons on the ground who were injured but all are recovering.

Another source of confusion was the testimony of witnesses, many of whom made conflicting statements. Of the approximately 40 already interviewed, for example, Lauber said about half reported seeing flames before the plane went down and half did not.

“They had different vantage points and different expectations,” he said.

Lauber noted that the experienced crew of another airplane, “waiting to take off and in a good angle to see,” reported no signs of fire.

Although most of the investigative personnel deployed here Wednesday were NTSB specialists, outsiders have been invited to help wherever appropriate.

Among others, FAA experts are assisting with air traffic control data, Air National Guard personnel from nearby Selfridge airfield are providing backup radar data, the National Weather Service is providing meteorological information, McDonnell Douglas and Pratt & Whitney are providing experts on the plane and its engines and the Air Line Pilots Assn. has volunteered its expertise.

In addition to providing investigators with documentation about the aircraft, its maintenance and flight crew, Northwest Airlines has assigned a “manager” to the family of each victim to aid in transportation accommodations or any other needed service, according to the airline.

Security at the crash site--and a major part of the ugly task of recovering the victims--has been undertaken by local law enforcement, primarily the Wayne County Sheriff’s Department and the Romulus city police.

Most of the recognizable body fragments had been recovered Wednesday--their points of discovery marked, ironically, by gaily waving little yellow flags amid the gray of the charred wreckage. But members of the NTSB’s structures group--charged with documenting the sequence in which the big plane broke up after impact--were still recovering small fragments of human remains Wednesday afternoon as they finished up the job of prying apart the mangled debris.

As is routine in the investigation of air crashes, tissue samples from the pilot and co-pilot have been taken to determine if either was under the influence of drugs or alcohol.